Electrode for arc-lights.



G. P. STEINMETZ. ELECTRODE FOR ARC LIGHTS.

APPLICATION FILED FEB. 26, 1902. RENEWED FEB. 26,1904.

Patented Mar. 9, 1909.

VVztnesses;

Z (1. d .MWWJ S UNITED STATES PATENT OFFICE.

CHARLES P. STEINMETZ, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRODE FOR ARC-LIGHTS.

Spepification of Letters Patent. 4

Patented March 9, 1909.

Application filed February 26, 1902, Serial No. 95,804. Renewed February 28, 1904. Serial No. 195,481.

To all whom it may concern:

Be it known that I, CHARLES P. STEIN- METZ, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Im' rovements in Electrodes for Arc-Lights, 0 which the following is a specification.

My present invention relates to improvements in electric arc lights and more espe-- cially to the composition of the terminals or electrodes used therein. When the terminals or electrodes are of carbon, as is now the common practice, the arc itself is of comparatively feeble intensity, the greater portion of the light being derived from the incandescent crater of the positive terminal. I have discovered however that if either or both of the terminals be made either in whole or in part of magnetite (Fe O instead of carbon, the arc assumes an entirely difierent character. Instead of being the minor factor in the production of light it becomes intensely luminous, giving off a brilliant white light with a spectrum like that of iron. If both electrodes or terminals are of magnetite it is immaterial which is positive and which is negative. If, however, one terminal be of carbon or of some substance-other than magnetite, it is desirable that the magnetite terminal should be the negative. If, with one electrode of carbon and the other of magnetite, the polarity be reversed so that the magnetite is the positive terminal and the carbon the negative terminal, the are instead of being of the luminous character mentioned, becomes dull and com aratively non-luminous and yellowish in co or, the spectrum under these circumstances presenting bright sodium and potassium lines, showing the presence of these substances as impurities.

The use of magnetite for the purposes above described not only very greatly imroves the quantity and character of the ight, but possesses in addition the valuable feature that electrodes formed thereof waste away only very slowly, considerably slower in fact than the wasting away of correspondby Letters Patent of the United States, is,

1. An arc lamp electrode in which magne tite predominates. I

2. An arc lamp electrode composed of magnetite.

3. An arc lamp electrode composed predoirdn'nantly of a good conducting metallic 0X1 4. An arc lamp electrode composed predominantly of a metallic oXid of good conductivity and which when heated is but slightly attacked by air.

5. An arc lamp electrode which is a good conductor at ordinary temperatures, and contains a good conducting metallic oxid giving a luminous or flaming arc.

6. An arcing electrode composed essentially of an electrically conducting oxid.

7. An arcing electrode composed essentially of an oxid of iron.

8. An arcing electrode composed tially of the magnetic oxid of iron.

9. An essentially metallic arcing electrode containing oxid of iron.

10. An essentially metallic arcing electrode containing magnetic oxid of iron.

11. An are light electrode composed principally of magnetite.

1 2. An arc light electrode containing at least 75 per cent. of magnetite.

In witness whereof, I have hereunto set my my hand this 24th day of February, 1902.

- CHARLES P. STEINMETZ.

Witnesses:

' HELEN ORFoRn,

ALEX. F. MACDONALD. 

